Polymer composition

ABSTRACT

A blend of at least one boron, phosphorus or sulphur containing acid which may contain amino, hydrocarbyl or hydrocarbylamino substituents and a polypropylene/unsaturated carboxylic acid or anhydridge graft copolymer has adhesive properties similar to those of the graft copolymer alone. The blend is readily produced and can be used in a fibre reinforced thermoplastic material or in blends of an olefine polymer with a different type of polymer such as a polyamide or polyester. Suitable acids include phenyl boric acid, phenylphosphonic acid, diphenylphosphinic acid, sulphanilic acid, toluene sulphonic acid, phenylhydrazine-p-sulphonic acid, d-10-camphor sulphonic acid, orthanilic acid, hypophosphorus acid, sulphosalicylic, and particularly sulphamic acid. The graft copolymer is preferably a polypropylene/maleic anhydride graft copolymer.

This is a division, of application Ser. No. 415,122 filed Nov. 12, 1973,now U.S. Pat. No. 3,997,503.

The present invention relates to polymer compositions and in particularto compositions suitable for promoting adhesion between polyolefinesespecially polypropylene, and other materials.

The polymers and copolymers of the olefine monomers possess a usefulcombination of mechanical properties coupled in many cases with chemicalinertness to many environments. The polymers of ethylene and propyleneare used extensively commercially in view of their useful combination ofproperties. However, although the chemical inertness of these polymersis very desirable and useful in many applications, this inertness makesit difficult to form a bond between the olefine polymer and anothermaterial. Adhesives have been developed to overcome this difficulty, andsuch adhesives include graft copolymers obtained by grafting, onto anolefine polymer, an ethylenically unsaturated monomer containing atleast one carboxylate group.

According to the present invention there is provided a polymericcomposition which comprises a blend of (a) a graft copolymer obtained bygrafting an unsaturated dicarboxylic acid or the anhydride thereof ontoa propylene polymer and (b) at least one compound selected fromsulphur-containing acids having the formula I, phosphorus-containingacids having the formula II, and boron-containing acids having theformula III,

    rso.sub.n H                                                I

    r'r"po(oh)                                                 ii

    rb(oh).sub.2                                               iii

wherein 1-90% of the acid moieties of the blend are present in the acidand/or anhydride component of the graft copolymer,

R is NR₂ '", a hydrocarbyl group, or a substituted hydrocarbyl group andwhen the compound (b) is an acid of formula I and the group is anaromatic group, any substituent containing an atom other than carbon,hydrogen or oxygen is located in a position which is other than meta- tothe --SO_(n) H group;

R' is hydrogen or substituted or unsubstituted hydrocarbyl;

R" is OH or a group R';

R"' is H or a hydrocarbyl group; and

n is 2 or 3;

Except that R' is not hydrogen when R" is OH.

A wide range of acids of boron, phosphorus or sulphur can be used ascomponent (b) of the blend. Thus, component (b) can be a boric acidderivative such as phenyl boric acid. Alternatively, the acid can be asulphonic acid derivative containing an, optionally substituted, aminogroup, such as phenylhydrazine-p-sulphonic acid or particularlysulphamic acid. Other suitable sulphonic acids include the hydrocarbylsulphonic acid such as p-toluene sulphonic acid andnaphthalene-2-sulphonic acid, and the substituted hydrocarbyl sulphonicacids such as sulphosalicylic acid(3-carboxy-4-hydroxy-benzene-sulphonic acid), d-10-camphor sulphonic,orthanilic and sulphanilic acids. The sulphur-containing acid can be asulphinic acid such as phenyl sulphinic acid. Suitablephosphorus-containing acids include hypophosphorous, phenyl phosphonicand diphenylphosphinic acids.

If a sulphur-containing acid is used as component (b) of the blend, thegroup R is conveniently a substituted or unsubstituted aryl groupparticularly one having no more than two substituent groups attached toany one ring, for example a 3-carboxyl-4-hydroxyphenyl, p-aminophenyl orp-tolyl group. Alternatively the group R is very conveniently theamino-group -NH₂.

If a phosphorus-containing acid is used, at least one of the groups R'and R" is conveniently an aryl group. Alternatively, both the groups R'and R" are very conveniently hydrogen.

Component (a) of the blend can be any graft copolymer which is effectiveas an adhesive, such copolymers including the product of grafting maleicacid, itaconic acid, maleic anhydride or Δ⁴-3,6-endomethylene-tetra-hydrophthalic anhydride onto a propylenepolymer. Graft copolymers of maleic anhydride and a propylene polymerare available commercially and are thus particularly convenient for useas component (a) of the blend.

Thus, as a further aspect of the present invention there is provided apolymeric composition comprising a blend of (a) a graft copolymerobtained by grafting maleic anhydride onto a propylene polymer and (b)at least one compound selected from sulphur-containing acids having theformula I, phosphorus-containing acids having the formula II, andboron-containing acids having the formula III

    rso.sub.n H                                                I

    r'r"po(oh)                                                 ii

    rb(oh).sub.2                                               iii

wherein 1 to 90% of the acid moieties of the blend are present in themaleic anhydride of the graft copolymer, and R, R', R" and n are ashereinbefore defined.

Preferably from 25 up to 80% of the acid moieties ar present as the acidand/or anhydride component of the graft copolymer.

The propylene polymer, onto which the unsaturated dicarboxylic acid oranhydride is grafted, is preferably a crystalline polymer and may be ahomopolymer or a copolymer with a minor proportion, for example up to25% by weight, of another olefine monomer, such as ethylene.

The blend can be used in a similar manner to the graft copolymer aloneeither as an adhesive or to improve compatibility between materials andwe have found that the properties of some blends are very similar tothose of the graft copolymer alone. The blend can be used to providebonding between a propylene polymer and an inorganic filler such as aglass fibre as described in British Pat. Nos. 1,095,700 and 1,174,943.The blend can be used in the production of a filled polymer compositionusing any suitable technique for producing such compositions and isparticularly useful when used to produce a fibre reinforcedthermoplastic material, for example glass fibre reinforced polypropyleneusing the process of German Patent application No. 2,117,095.

Alternatively, the blend can be used to improve the compatibilitybetween two materials, particularly plastics materials, and isespecially useful for improving compatibility between an olefinepolymer, such as an ethylene polymer or particularly a propylenepolymer, and another polymer, such as a polyamide or polyester, which isnot readily compatible with the olefine polymer.

The effectiveness of the blend as an adhesive is very convenientlydetermined by measurement of the tensile strength of a moulding formedfrom a composition comprising glass fibre, a propylene polymer and theblend. Mouldings are formed using only the grafted polymer as anadhesive and also using a blend of one or more boron-, sulphur- orphosphorus-containing acids and the grafted polymer as an adhesive. Thetensile strengths of the moulding are determined and the differencebetween the tensile strengths gives an indication of the effectivenessof any particular acid. An improvement of less than 0.3 kpsi in tensilestrength is not regarded as being a significant improvement. Animprovement of at least 0.3 kpsi indicates that the acid is effective inimproving adhesive and materials giving improvements in this rangeinclude phenyl boric acid, orthanilic acid, sulphanilic acid, p-toluenesulphonic acid, phenylhydrazine-p-sulphonic acid, d-10-camphor sulphonicacid, naphthalene-2-sulphonic acid, phenyl phosphonic acid,diphenylphosphinic acid and phenyl sulphinic acid. It is preferred thatthe improvement obtained should be greater than 1.5 kpsi and such aneffect can be obtained with hypophosphorous, sulphamic andsulphosalicylic acids.

the blend of the present invention is particularly useful for inclusionin filled propylene polymers.

According to a further aspect of the present invention there is provideda compostion comprising an inorganic filler, a crystalline propylenepolymer and a blend of (a) a graft copolymer obtained by grafting anunsaturated dicarboxylic acid or the anhydride thereof, preferablymaleic anhydride, onto a propylene polymer, and (b) at least onecompound selected from sulphur-containing acids having the formula I,phosphorus-containing acids having the formula II and boron-containingacids having the formula III

    rso.sub.n H                                                I

    r'r"po(oh)                                                 ii

    rb(oh).sub.2                                               iii

wherein in said blend 1 to 90%, and preferably between 25 and 80%, ofthe acid moieties are present as the acid or anhydride component of thegraft copolymer, and R, R', R" and n are as hereinbefore defined.

Such a composition can be used in the manner well known in the art forthe production of injection moulded articles and the like, for examplefans, impellers filters and motor car components.

The inorganic filler is conveniently a fibrous reinforcing material suchas glass fibre. If the filler is glass fibre it should be coated with asilane containing at least one substituent which is reactive with thefiller and at least one acid reactive organic substituent. Thesubstituent which is reactive with the filler may be hydroxy, alkoxy, orhalide and is preferably hydroxy or alkoxy. The acid reactive organicsubstituent may be epoxy, hydroxy, amino, hydroxyalkyl, isocyanate ormercapto and is preferably hydroxy, epoxy or amino. Silanes which can beused to coat the filler include epoxyethyltriethoxy silane,γ-glycidoxypropyltrimethoxy silane, glycidoxyethyltriethoxy silane,1,2-epoxbutyltriethoxy silane, 1,2-epoxybutoxy-propyltriethoxy silane,β-(3,4-epoxycyclohexyl) ethyltrimethoxy silane, γ-aminopropyltriethoxysilane, aminoethyltriethoxy silane, γ-aminobutyltriethoxy silane andbis(β-hydroxyethyl)-γ-aminopropyltriethoxy silane.

The blend of one or more of boron-, sulphur- and phosphorus-containingacids and grafted propylene polymer may be prepared by any of the knownblending techniques. A suitable technique is to dissolve the acid in asuitable solvent, preferably one having a low boiling point, mix thesolution of acid with the solid graft copolymer and then evaporate offthe volatile solvent. Suitable solvents for this purpose include water,acetone, benzene, ethyl acetate and chloroform. Many suitable acids aresolid materials and for such materials a conventional solid mixingtechnique, for example using a high speed mixer, can be used to producethe blend.

The graft copolymer can be prepared using any of the known techniques.Suitable methods for carrying out grafting include radiation grafting,solution grafting using a free radical initiator and/or an oxidisedpolymer, extrusion grafting or fluidised bed grafting. Using anextrusion grafting technique it is preferred to use a free radicalinitiator but under the conditions used some grafting may result fromthe presence of a minor proportion of oxygen which is present in thepolymer. Graft copolymers containing an acid, for example maleic acid,can be prepared either by grafting the acid onto a propylene polymer orby the hydrolysis of a copolymer of a propylene polymer and a suitablederivative of the acid such as an anhydride of the acid, for example amaleic anhydride graft copolymer can be hydrolysed to give a maleicgraft copolymer.

When the graft copolymer is one containing grafted maleic anhydride, itshould contain at least 0.01% and preferably at least 0.4% by weight ofgrafted maleic anhydride. In general graft copolymers containing morethan 6% by weight of grafted maleic anhydride do not have significantlybetter properties than polymers with a lower content of grafted maleicanhydride. Depending on its method of preparation and purification, thegraft copolymer may contain a proportion of free unsaturateddicarboxylic acid or anhydride and such a material can be used ascomponent (a) of the blend of the present invention.

When using a blend of an acid and a maleic anhydride graft copolymer,althrough a significant improvement (compared to the acid alone) isobtained with only 25% by weight of the acid moieties present as themaleic anhydride of the graft copolymer, in some cases we have foundthat a slight further improvement is obtained as the proportion ofgrafted maleic anhydride is increased to provide about 50% of the acidmoieties. In general, above this level of grafted maleic anhydridelittle further singificant improvement occurs.

In the polymer composition comprising inorganic filler, crystallinepropylene polymer, a boron-, sulphur-or phosphorus-containing acid ormixture of such acids and graft copolymer, satisfactory properties areobtained when the total of acid moieties present is in an amount as lowas that provided by 0.01% by weight of maleic anhydride based on thepolymer content of the composition, althrough it will be appreciatedthat this is dependent on the relative proportions of filler andcrystalline propylene polymer, the nature of the filler, the type ofgraft copolymer and also the particular boron-, sulphur- orphosphorus-containing acid or mixture thereof used. Thus, it ispreferred that the total amount of acid moieties is at least 0.01% byweight of the polymer content of the composition and for most systemsthe amount of total acid moieties is in the range 0.02 to 1.0% by weightof the polymer content of the composition. When the filler is glassfibre and a blend of acid and a maleic anhydride grafted copolymer isused, we have found that satisfactory mechanical properties are obtainedwith a total of acid moieties which is equivalent to that provided by0.04% by weight of maleic anhydride and of which from 25 up to 80% byweight are present in the grafted maleic anhydride. Althoughsatisfactory mechanical properties can be obtained at the sameconcentrations with most of the defined boron-, sulphur- orphosphorus-containing acids, it will be realised that the effectivenessof a given acid is dependent on the nature of the particular acid andthe optimum level of the acid will be influenced by the acid actuallybeing used. A different graft copolymer can be used to replace themaleic anhydride graft copolymer at the same concentration but, in thiscase also, the optimum level of the graft copolymer will be dependent onthe particular acid or anhydride which is in grafted form and theeffectiveness of any graft copolymer is more properly considered on thebasis of the number of carboxylic acid groups present rather than theproportion by weight of the grafted acid or anhydride in the copolymer.

The present invention will now be described by reference to thefollowing Examples which are illustrative of the invention but notlimiting.

EXAMPLES 1 - 12

A masterbatch containing 4% by weight of a boron-, sulphur- orphosphorus-containing acid, based on the weight of the masterbatch, wasprepared by mixing the acid, in solid form, and unstabilised crystallinepolypropylene powder in a high speed mixer. When hyposphorus acid wasused the masterbatch was prepared by adding the acid in the form of a50% by weight aqueous solution and then drying the polymer powder in avacuum oven at 50° C.

A graft copolymer of polypropylene and maleic anhydride containing 3.6%by weight of grafted maleic anhydride and a negligible proportion (lessthan 0.1% by weight) of free maleic anhydride, was blended in a highspeed mixer with the polypropylene/acid masterbatch.

The blend thus obtained was then mixed with crystalline polypropylenepowder and glass fibre by tumble blending to give a composition in whichthe level of grafter maleic anhydride was 0.01% by weight based on theweight of polymer and the glass fibre content was 20% by weight of thetotal composition. The glass fibre was 0.25 inch long chopped fibre of0.0005 inch diameter and was coated with γ-aminopropyltriethoxy silane.The composition thus obtained was injection moulded at a temperature of240° C to give tensile bars whose strengths were determined using ASTMTest D638-68 modified by using a temperature of 20° C and an extensionrate of 1.0 inch per minute. The results obtained using variousdifferent acids are set out in Table 1 in which comparative results,using only the grafted polymer, or in the absence of any adhesive, arealso detailed.

                                      TABLE 1                                     __________________________________________________________________________                              Proportion                                                                    of grafted                                                              Proportion                                                                          maleic                                              Example             of    anhydride                                                                           Tensile                                       or                  acid in                                                                             present in                                                                          strength                                      Comparative         polymer                                                                             polymer                                                                             (kilopounds                                   Example                                                                                Acid Type  (wt %)                                                                              (wt %)                                                                              sq. in.)                                      __________________________________________________________________________    1      Phenylboric  0.1   0.01  11.4                                          2      Sulphamic    0.06  0.01  12.6                                          3      Sulphamic    0.1   0.01  12.9                                          4      Sulphanilic  0.06  0.01  11.4                                          5      Orthanilic   0.1   0.01  11.9                                          6      p-toluene sulphonic                                                                        0.06  0.01  12.2                                          7      Phenylhydrazine-p-                                                                         0.1   0.01  11.5                                                 sulphonic                                                              8      Sulphosalicylic                                                                            0.1   0.01  12.7                                          9      d-10-camphor sulphonic                                                                     0.1   0.01  11.5                                          10     Hypophosphorous                                                                            0.1   0.01  12.6                                          11     Phenyl phosphonic                                                                          0.04  0.01  12.1                                          12     Diphenyl phosphinic                                                                        0.13  0.01  11.6                                          A      NIL          0     0.01  10.9                                          B      NIL          0     0.04  13.3                                          C      NIL          0     0     7.3                                           __________________________________________________________________________

It will be seen from Table 1 that the acids specified all gave animprovement in tensile strength of greater than 0.3 kilopounds/sq. inch(kpsi) compared to the result obtained using the graft copolymer aloneat the same level of graft copolymer (see Comparative Example A). Itwill also be seen that some of the acids gave a tensile strengthcomparable with the result obtained using 0.04% of grafted maleicanhydride as the only adhesive (see Comparative Example B and Examples2, 3, 8 and 10.

EXAMPLES 13 AND 14

The procedure described for Examples 1 to 12 was repeated usingdifferent acids. Naphthalene-2-sulphonic acid was added as a solidmaterial whilst the phenylsulphinic acid was added as an aqueoussolution in the same manner as the hypophosphorous acid. The resultsobtained are set out in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                              Proportion                                                                    of grafted                                                              Proportion                                                                          maleic                                              Example             of    anhydride                                                                           Tensile                                       or                  acid in                                                                             present in                                                                          strength                                      Comparative         polymer                                                                             polymer                                                                             (kolopounds                                   Example                                                                                Acid Type  (wt %)                                                                              (wt %)                                                                              sq. in.)                                      __________________________________________________________________________    13     Phenylsulphinic                                                                            0.1    0.01 12.2                                          14     Naphthalene-2-sulphonic                                                                    0.1   0.01  11.6                                          D      NIL          0     0.01  10.7                                          __________________________________________________________________________

We claim
 1. A polymeric composition comprising a blend of (a) a graftcopolymer obtained by grafting an unsaturated dicarboxylic acid or theanhydride thereof onto a propylene polymer, wherein the grafted acid oranhydride is present in an amount sufficient to give an acid moietywhich is at least equivalent to that provided by 0.01 percent by weightof maleic anhydride and (b) at least one acid selected from the groupconsisting of phosphorus-containing acids of the formula

    R'R"PO(OH)

wherein 1-90% by weight of the acid moieties of the blend of (a) and (b)are present in the acid and/or anhydride component of the graftcopolymer; and R' is hydrogen or substituted or unsubstitutedhydrocarbyl; and R" is OH or a group R'; except that R' is not hydrogenwhen R" is OH.
 2. The composition of claim 1 wherein from 25 up to 80%of the acid moieties of the blend of (a) and (b) are present as the acidand/or anhydride component of the graft copolymer.
 3. The composition ofclaim 1 wherein component (b) is selected from the group consisting ofhypophosphorous acid, phenylphosphonic acid and diphenylphosphonic acid.4. The composition of claim 1 wherein the graft copolymer is the productof grafting maleic acid, itaconic acid, Δ⁴-3,6-endomethylene-tetrahydrophthalic anhydride, or maleic anhydrideonto a propylene polymer.
 5. A polymeric composition which comprises thecomposition of claim 1, a propylene polymer and an inorganic filler. 6.The composition of claim 5 wherein the inorganic filler is glass fibrecoated with a silane containing at least one substituent which isreactive with the filler and at least one acid reactive organicsubstituent.
 7. The composition of claim 5 wherein the amount of totalacid moieties is in the range 0.02 1.0% by weight of the polymer contentof the composition.
 8. The composition of claim 5 wherein the component(b) is hypophosphorous acid.
 9. The composition of claim 2 whereincomponent (a) contains 0.4 to 6% by weight of grafted maleic anhydride.10. A process for the production of a polymeric composition whichcomprises mixing (a) a graft copolymer obtained by grafting anunsaturated dicarboxylic acid or the anhydride thereof onto a propylenepolymer wherein the grafted acid or anhydride is present in an amountsufficient to give an acid moiety which is at least equivalent to thatprovided by 0.01% by weight of maleic anhydride, with (b) at least oneacid selected from the group consisting of phosphorus-containing acidsof the formula

    R'R"PO(OH)

in proportions such that 1-90% by weight of the acid moieties of themixture of (a) and (b) are present in the acid and/or anhydridecomponent of the graft copolymer, and wherein R' is hydrogen orsubstituted or unsubstituted hydrocarbyl; and R" is OH or a group R';except that R' is not hydrogen when R" is OH.
 11. The process of claim10 wherein a propylene polymer and an inorganic filler are also mixedwith (a) and (b).